Incremental Adjustments to Amount of Thickening Agent in Beverages: Implications for Clinical Practitioners Who Oversee Nutrition Care Involving Thickened Liquids

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Article Incremental Adjustments to Amount of Thickening Agent in Beverages: Implications for Clinical Practitioners Who Oversee Nutrition Care Involving Thickened Liquids

Jane Mertz Garcia 1,* and Edgar Chambers IV 2

1 Communication Sciences & Disorders, School of Family Studies & Human Services, Kansas State University, 1405 Campus Creek Road, Manhattan, KS 66506, USA 2 Center for Sensory Analysis and Consumer Behavior, 1310 Research Park Dr., Manhattan, KS 66502, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-785-532-1493

Received: 3 January 2019; Accepted: 12 February 2019; Published: 14 February 2019

Abstract: This study examined the changes in viscosity in response to small alterations in the amount of a thickening agent mixed with three commonly thickened beverages. A total of 11 incremental adjustments in the amount of a starch-based thickening agent (5.0 g to 7.0 g) were made. The results showed that the incremental increases resulted in systematic changes to the liquid thickness, reflecting modifications that ranged from a nectar (mildly thick) to a honey-like (moderately thick) level of consistency. The findings emphasize the importance of the proper preparation of thickened beverages, highlighting the need for standards in training practices and the use of simple measurement tools for assuring the prescribed levels of consistency.

Keywords: dysphagia; swallowing; thickened beverages; liquids; viscosity; quality of care

1. Introduction The nutritional care of patients with dysphagia who consume thickened beverages requires the careful preparation of drinks to their prescribed level of modification. Basic care staff (e.g., dietary aides, cooks, and certified nursing assistants) are typically tasked with preparing modifications even though they reportedly receive little or no formal instruction about thickened liquids [1,2]. Although a number of modified beverages are currently available in ready-to-serve form, thickening liquids with commercial thickeners that require preparation by caregivers are a cornerstone of nutrition care in many settings [3,4]. One practical concern about the preparation of thickened beverages is the lack of adherence to product guidelines when determining the amount of thickening agent to mix into a beverage. Garcia et al. [2] found that many of the care staff did not look at the product label information to determine the specified amount of thickening agent. Unsurprisingly, the modifications they prepared varied considerably in terms of measured viscosity when compared to similar product/beverage combinations made in a laboratory environment using controlled conditions [2]. Even speech-language pathologists (who are experienced in dysphagia management) have difficulty preparing thickened beverages in a reliably consistent manner [5]. This inability to prepare thickened liquids consistently is a cause for concern because of the health implications linked to over- or under-thickening the beverage of patients. Clinical practitioners are encouraged to recommend the least viscous modification that is swallowed safely, which further magnifies the importance of careful preparations [6–8]. Inaccuracies

Foods 2019, 8, 74; doi:10.3390/foods8020074 www.mdpi.com/journal/foods Foods 2019, 8, 74 2 of 7 in preparation increase the risk of additional medical complications. For example, overly thickened beverages are more difficult for frail elders to clear from their airway, heightening the risk of pulmonary complications or aspiration pneumonia [9]. Such problems may occur in patients with impaired swallowing or a diminished ability to cough. Overly thick modifications also contribute to post-swallow residues in the pharynx [7,8]. Because the addition of a thickening agent affects the flavor and texture of a drink in a potentially negative way [10,11], caregivers who routinely overly thicken may create a modification that impacts the beverage’s acceptance. Patients with a strong dislike of the thickened beverages may, as a result, be less compliant and drink less, ultimately impacting their nutritional status. This occurs through a decreased consumption of juices, liquid nutritional supplements and other beverages. Additionally, a reduced consumption of beverages also can contribute to other medical complications such as dehydration, especially if water the consumption decreases. Although the concern regarding preparation inaccuracies is clear, less is known about how small variations in the amount of thickening agent impact physical measures of viscosity. Park et al. [12] already evaluated various levels of gum-based thickeners, both guar and xanthan, showing that the viscosity of guar gum thickened liquids changed more rapidly than that of xanthan gum as the concentration increased, perhaps because of shear thinning. Such results suggest that in some cases inadvertent changes in thickening, such as might occur when beverages are mixed improperly, could result in large changes in viscosity. Because no work has been found examining incremental changes in starch-based thickeners, the goal of this study was to understand how incremental changes in the amount of starch-based thickening agents contributed, if at all, to viscometer readings for different modified beverages.

2. Materials and Methods We selected Thick & Easy (Hormel Health Labs, Austin, MN, USA), a commercial thickening agent commonly used in modifying liquids for patients with dysphagia. The product ingredients listed modiﬁed corn starch and maltodextrin. The three beverages included water, apple juice (Musselman’s, Peach Glen, PA, USA) and cran-apple juice, a commercial blend of apple and cranberry juice (Ocean Spray, Lakeville-Middleboro, MA, USA). The beverages represented common drinks in care facilities that are easily mixed (no clumping) with a thickening agent. All have quite a low viscosity (cps 0–2). It must be noted that for this project a variety of samples could have been selected. We intentionally chose to keep the study small and focus on one thickener, a starch-based product that is widely used in dysphagia management in the United States. Gum-based thickeners are also widely used, but typically they are more difﬁcult to mix, and this would present an added variable to this study. In addition, Park et al. [12] already evaluated various levels of gum-based thickeners.

2.1. Sample Preparation Procedure The volumetric amount of liquid (120 mL) was converted into grams to ensure the same amount of beverage for each sample. The amount of thickening agent (also measured in grams) was slowly poured and stirred into the base liquid at room temperature (20–22 ◦C) and then continuously stirred for 40 s until it dissolved using a Barnstead Thermolyne magnetic stirring device (Cimarec 2) set to a constant speed. We systematically increased the amount of thickening agent by 0.2 g (e.g., 5.0 g, 5.2 g, 5.4 g, and 5.6 g) in each subsequent test sample. An increase of 0.2 g equated to slightly less than a 1mL (1/8 tsp) measuring spoon difference of thickening agent. Three separate samples were prepared for 11 incremental changes in thickening agent (5.0 g to 7.0 g) across beverages. The lowest to highest amount of instant thickening agent (a difference of 2.0 g) represented a difference of about 1 7.5 mL (by volume) of powdered thickener (equivalent to about 1 2 tsp, a common measure in the US). The thickness ranged from nectar-like (mildly thick) to honey-like (moderately thick), including the border of the two thickness levels (Figure1). Foods 2019, 8, 74 3 of 7 Foods 2019, 8, x FOR PEER REVIEW 3 of 7

1 Figure 1.FigureVisual 1. Visual comparison comparison of 5.0of 5.0 g (3g (32 ½tsp) tsp) and 7. 7.00 g (5 g (5tsp) tsp) of instant of instant thickening thickening agent. agent.

2.2. Viscosity2.2. MeasurementViscosity Measurement ViscosityViscosity was measured was measured using using a Brookfielda Brookfield RVDV- II+ II+ viscometer viscometer using usingthe small the sample small sample adaptor andadaptor calculated and calculated at a shearat a shear rate rate of of 55.8 55.8 toto be consistent consistent with with instrument instrument guidelines guidelines and and modification ranges described by the National Dysphagia Diet [13]. The samples were measured at modificationroom ranges temperature described (20–22 °C) by after the two National minutes Dysphagiaof thickening time. Diet The [13 measurements]. The samples were were collected measured at ◦ room temperaturefor a total of (20–22 99 samplesC) after(11 changes two minutesin gram amount of thickening × 3 beverages time. × 3 replicates). The measurements were collected for a total of 99 samples (11 changes in gram amount × 3 beverages × 3 replicates). 2.3. Statistical Analysis 2.3. Statistical AnalysisWe entered the data into the IBM SPSS System for Windows (IBM, New York, USA, Version 25, 2017); a “descriptive” statistics procedure was used to determine the means and standard deviations We enteredfor each thegram data amount into and the for IBM each SPSSbeverage System over the for three Windows replicates. (IBM, The gram New measurements York, USA, and Version 25, 2017); a “descriptive”physical measurements statistics of procedureviscosity of each was beverage used towere determine compared using the means Pearson and product-moment standard deviations for each gramcorrelation amount coefficients and for with each a significance beverage at overthe 0.01 the level three (2-tailed). replicates. The gram measurements and physical measurements3. Results of viscosity of each beverage were compared using Pearson product-moment correlation coefficients with a significance at the 0.01 level (2-tailed). Table 1 shows the average measurement of viscosity in centipoise (cP) for the three beverages prepared with 5.0 to 7.0 g of instant thickener. The mean values changed for each increase in the 3. Resultsamount of thickening agent; higher values represented more viscous (thicker) samples. The gram Tablemeasurements1 shows the and average physical measurement measurements of of visc viscosityosity correlated in centipoise significantly (cP) for for thickened the three water beverages (r = 0.97, p < 0.01), apple juice (r = 0.98, p < 0.01), and cran-apple juice (r = 0.98, p < 0.01), as visually prepared withdepicted 5.0 in to Figure 7.0 g2. ofStarting instant at 5.4 thickener. g of thickener, The significant mean values differences changed were noted for eachbetween increase the in the amount ofjuice thickening (both samples) agent; and higherwater, with values water represented thickening to a morehigher viscousdegree at a (thicker) faster pace samples. than either The gram measurementsof the juice and samples physical did. measurements Significant differences, of viscosity although much correlated smaller, significantlywere also noted forbetween thickened the water (r = 0.97, papple< 0.01), and cran-apple apple juice juice (r at= 6.0 0.98, and p6.2< g, 0.01), and again and at cran-apple 6.8 and 7.0g. juice (r = 0.98, p < 0.01), as visually depicted in FigureTable2 1.. StartingViscosity measurements at 5.4 g of thickener,in cP for the bevera significantges mixed differences with incremen weretal increases noted in between the the juice (both samples)amount and water,of instant with thickening water agent. thickening to a higher degree at a faster pace than either of the Apple Juice Cran-apple Juice Water juice samples did.Thickening Significant Agent (in Grams) differences, although much smaller, were also noted between the apple Mean (Stf Dev.) Mean (Std. Dev.) Mean (Std.Dev.) and cran-apple juice at5.0 6.0 g and 6.2 g, and again 123.6 at(2.7) 6.8 and 7.0 g. 136.9 (8.0) 130.0 (5.4) 5.2 g 151.7 (1.7) 155.8 (9.3) 162.0 (6.2) Table 1. Viscosity measurements5.4 g in cP for 168.9 the (11.5) beverages mixed 180.5 with(5.0) incremental 198.6 increases (11.3) in the 5.6 g 199.7 (10.5) 214.7 (7.5) 253.3 (8.8) amount of instant thickening5.8 g agent. 221.7 (8.7) 233.9 (7.2) 292.8 (4.1) 6.0 g 265.6 (17.8) 292.8 (9.5) 330.9 (7.2) Thickening6.2 g Agent Apple Juice 293.1 (9.3) Cran-Apple Juice 318.3 (21.0) Water 423.1 (24.2) (in6.4 g Grams) Mean (Stf 358.9 Dev.) (11.5) Mean (Std. Dev.) 373.1 (15.8)Mean (Std. Dev.) 514.7 (30.1) 6.6 5.0g g 123.6 (2.7) 397.5 (8.8) 136.9 (8.0) 407.2 (14.5) 130.0 (5.4) 619.4 (17.9) 6.8 5.2g g 151.7 (1.7) 445.8 (9.0) 155.8 (9.3) 492.8 (26.7) 162.0 (6.2) 715.0 (38.8) 7.0 5.4g g 168.9 (11.5) 492.8 (9.3) 180.5 (5.0) 542.2 (5.4) 198.6 (11.3) 785.0 (18.6) 5.6 g 199.7 (10.5) 214.7 (7.5) 253.3 (8.8)

5.8 g 221.7 (8.7) 233.9 (7.2) 292.8 (4.1) 6.0 g 265.6 (17.8) 292.8 (9.5) 330.9 (7.2) 6.2 g 293.1 (9.3) 318.3 (21.0) 423.1 (24.2) 6.4 g 358.9 (11.5) 373.1 (15.8) 514.7 (30.1) 6.6 g 397.5 (8.8) 407.2 (14.5) 619.4 (17.9) 6.8 g 445.8 (9.0) 492.8 (26.7) 715.0 (38.8) 7.0 g 492.8 (9.3) 542.2 (5.4) 785.0 (18.6) Foods 2019, 8, 74 4 of 7 Foods 2019, 8, x FOR PEER REVIEW 4 of 7

900 800 700 600 500 400 300 Centipoise 200 100 0 5.0 5.2 5.4 5.6 5.8 6.0 6.2 6.4 6.6 6.8 7.0 Amount of Thickening Agent, g

Apple Juice Cran-apple Juice Water

Figure 2. Viscosity measurements for the incremental changes in the amount of instant thickening Figure 2. Viscosity measurements for the incremental changes in the amount of instant thickening agent (Error bars show the standard error for each mean). agent (Error bars show the standard error for each mean). 4. Discussion 4. Discussion The results highlight the finding that seemingly small, but carefully controlled alterations in the amountThe results of thickening highlight agent,the finding can impact that seemingly the physical small, measures but carefully of viscosity controlled in a alterations fairly systematic in the manner.amount of In thickening this study, agent, the viscosity can impact measurements the physical went measures from 123.6 of viscosity cP (thickened in a fairly apple systematic juice) to 785manner. cP (modified In this study, water), the consistent viscosity measurements with commonly we recommendednt from 123.6 cP modifications (thickened apple that range juice) fromto 785 a nectarcP (modified (mildly water), thick) consistent to honey-like with (moderately commonly re thick)commended consistency modifications [7,12]. Given that that range many from preparers a nectar are(mildly inattentive thick) to to honey-like the product (moderately label information thick) [co2],nsistency the clinical [7,12]. implication Given that is thatmany too preparers much or tooare littleinattentive thickening to the agent product (e.g., label level information vs. heaping [2], teaspoon) the clinical could implication result in ais modification that too much that or istoo unsafe little forthickening swallowing. agent (e.g., level vs. heaping teaspoon) could result in a modification that is unsafe for swallowing.A generally similar pattern of change occurred across different beverages (Figure2), although the juiceA products generally had similar less thickening pattern of withchange higher occurred levels across of starch-based different beverages thickener. (Figure This may 2), reflect although the interactionthe juice products of the setting had less time thickening (2 min) and with absorption higher levels characteristics of starch-based of a starch-thickening thickener. This agentmay reflect when beveragesthe interaction contain of the other setting components time (2 min) such and as sugar, absorption acid or characteristics the small amounts of a starch-thickening of pectin remaining agent in bottledwhen beverages juice. Both contain sugar andother acid components can reduce viscositysuch as sugar, when combinedacid or the with small starch amounts [14]. In of this pectin case, theremaining sugar content in bottled of thejuice. juice Both may sugar have and reduced acid can the reduce water viscosity uptake bywhen the combined starch because with bothstarch sugar [14]. andIn this starch case, compete the sugar for content the same of the water. juice Acid may can have result reduced in the the breakdown water uptake of the by starch the starch molecules because by theboth hydrolysis sugar and of starch the glycosidic compete bondsfor the between same water. the glucose Acid can molecules result in that the make breakdown up the starchof the [15starch,16], althoughmolecules that by the typically hydrolysis happens of the over glycosidic a much longerbonds periodbetween of the time glucose than the molecules duration that implemented make up the in thisstarch experiment. [15,16], although The small that amount typically of pectin happens remaining over a much in clarified longer bottled period juices, of time such than as thosethe duration used in theimplemented experiment, in probablythis experiment. would have The littlesmall impact amount on of thickness. pectin remaining in clarified bottled juices, such as those used in the experiment, probably1 would have little impact on thickness. Small changes of 0.2 g (less than 4 teaspoon) impacted the physical measurement of viscosity, but itSmall is less changes clear if thoseof 0.2 differencesg (less than are ¼ detectableteaspoon) toimpacted oral perception the physical [17]. measurement These authors of did viscosity, suggest thatbut it at is least less 4clear levels if those of detectible differences difference are detectable could probably to oral perception be noted within [17]. These the nectar-thick authors did category suggest alone.that at least They 4 also levels noted of detectible the exponential difference relationship could probably of thickener be noted to within thickness, the whichnectar-thick can be category seen in thisalone. study. They That also relationship noted the exponential shows that therelationship incremental of thickener differences to inthickness, thickness which typically can getbe smallerseen in forthis each study. unit That of relationship increased thickness. shows that Thus, the increm small incrementalental differences differences in thickness in the typically thickener get are smaller more importantfor each unit at lowerof increased levels thanthickness. at initially Thus, higher small levelsincremental of thickness. differences The in current the thickener study shows are more that important at lower levels than at initially higher levels of thickness. The current study shows that the relationship is beverage dependent. At higher levels of initial thickness, water showed more of an

Foods 2019, 8, 74 5 of 7 the relationship is beverage dependent. At higher levels of initial thickness, water showed more of an effect from small increases on the thickener than either of the juices did. Chambers et al. [18] showed that the textural properties of beverages of different thicknesses were clearly noted as thicker by descriptive sensory panelists.

5. Limitations We acknowledge that a number of factors may impact the reported ﬁndings. One consideration is that we examined one thickening product in dysphagia management, which may not be representative of the thickening patterns of other starch or gum-based thickening agents. However, prior research has shown that over time starch-based thickeners function similarly in many products [19]. Gum-based thickeners have been found to vary from a rapid change (guar gum) to a less rapid change (xanthan gum) in viscosity as the concentration increased [12]. In addition, these samples were tested at room temperature after two minutes of setting time. It is well established that the interaction of a number of factors (base liquid, serving temperature, thickening agent, and thickening time) impacts the viscosity of modiﬁed beverages [20–23]. However, the setting time always resulted in an increase in thickness over time [19], suggesting that these products would also increase in thickness if the time was increased, as might be the case in care settings where products sit before they are fully consumed by patients.

6. Conclusions Our results emphasize the need to properly prepare thickened beverages. A lack of information, support, and belief systems contribute to caregivers’ misuse of thickeners [24,25]. The results from this study further highlight the importance of instruction about modified beverages, especially since error patterns in preparation tend to be repeated across different levels of consistency [2]. For example, care providers who over-thicken nectar (mildly thick) beverages tend to over-thicken honey-like (moderately thick) preparations as well. A common myth held by some care providers, including nutrition specialists, is that “thicker is better” [3]. The practical consequence is that preparers who have this belief may tend to further adjust the amount of thickening agent due to this perception. This data also suggests that, in order to properly thicken a variety of beverages to a consistent level, more information is needed about their standard preparation. In addition to standard education and training practices, simple measurement tools, such as the IDDSI (International Dysphagia Diet Standardization Initiative) flow test [26] or a line spread apparatus offer objective information to practitioners about the thickness of thickened beverages [4,25,27]. Although a more sophisticated research tool was used for this project, simple tools that are reliable and easy to implement have the potential to aid instruction about a target level of consistency and to address quality assurance about the accuracy of day-to-day preparations. The impact of incremental fluctuations in the amount of thickening agent furthers our understanding about the importance of developing more consistent and effective training practices and instituting the use of simple measurement tools in clinical practice for best practices in nutrition care.

Author Contributions: J.M.G. and E.C.IV conceived and designed the experiments; J.M.G. performed or supervised all measurements; J.M.G. analyzed the data; J.M.G. prepared the manuscript; E.C.IV edited the manuscript. Funding: This research was funded, in part, by the Kansas State University Foundation Perry C. & Virginia Peine Excellence for Aging Initiative and Kansas State University Research and Extension Hatch project 1016242 from the National Institute for Food and Agriculture, USDA. Acknowledgments: The authors would like to Marcie Corpstein for her help in the lab work. Conﬂicts of Interest: The authors declare no conﬂict of interest. Foods 2019, 8, 74 6 of 7

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